1. Field of the Invention
The present invention relates to a composition with non-Newtonian behaviour, to a process for its preparation, to coated substrates obtainable with the compositions, and to the use of these coated substrates.
2. Discussion of Background Information
It is common knowledge that the rheology of coating solutions can be influenced by adding particulate solids. This knowledge is utilized, for example, in the case of wall paints, which, using pigments or other particles (e.g. Aerosil), are given a pseudoplastic formulation so that they do not drip and do not develop runs. Similar effects are known, too, for nanocomposites which comprise nanoscale particulate solids. The general rule here is that, the greater the amount of particles, the greater the extent to which the rheology can be influenced. It is not always possible, though, or is a disadvantage, to use such high particle concentrations. For example, the composite material becomes too brittle as a result, or too expensive, or high particle contents may even lead to unwanted side-effects, owing to the particle properties. There is therefore a need for a tool for adjusting the rheology that is independent of the particle concentration. It has surprisingly been found that it is possible to adjust the rheology independently of the particle concentration by purposively varying the surface charge of the particles in nanoparticulate dispersions, which may constitute a sol, for example.